a strategic board game for 3 persons, where all is well-situated to the number 3: three different shapes for the pieces-three different sizes for the pieces-three different sorts of wood-three boards for three players; in 2012 the game THREE won the Toy Award
have a look here: http://www.huchandfriends.de/page/en/Games/Games-Detail.php?oid=1009

and here: http://thebiggamehunter.com/main-menu-bar/about/games-by-bgh/

difficulty

the moves of the pieces and the capturing rules are very logical and can be deduced from the shapes and sizes of the pieces